Eyewear is often designed to fit closely to the wearer's face so as to block light, wind, water or dust from entering the area behind the lens or lenses. This also tends to trap moisture, which can result in fogging of the lens or lenses. The tendency for fogging can be reduced by the provision of vents which allow moist air to escape the area behind the lens or lenses.
A number of venting techniques have been employed for eyewear. For example, U.S. Pat. No. 6,233,342 discloses eyewear for use in sports and the like which allows the user to adjust the flow of air across the inside surface of the lens without having to remove the eyewear. Ventilation apertures are preferred to be covered with permeable foam to prevent the ingress of dust and particulate matter through the apertures. A sliding block provides control over airflow. This eyewear has a drawback in that moving parts are required to control airflow and the foam for covering the ventilation apertures contribute to increased complexity of the eyewear and, thus, cost of manufacture.
U.S. Pat. No. 5,969,787 discloses eyewear with browbar ventilation and detachable temples. A browbar frame is detachably secured to a lens and temples are detachably secured to the browbar frame. The browbar frame includes numerous openings to allow air to pass through the browbar frame for preventing fogging of the lens. This eyewear has a disadvantage that light is not inhibited from entering behind the lens area through the ventilation openings.
U.S. Pat. No. 5,760,868 discloses eyewear having a ventilated frame including air inlets on lateral sides of the frame. This eyewear also has a disadvantage in that light is not inhibited from entering behind the lens area through the air inlets.
Therefore, what is needed is an improved technique for eyewear ventilation which is not excessively complex to manufacture and that inhibits light from entering behind the lens area of the eyewear or into the wearer's eye.